I have ordered Alpha and CTS potentiometers that should arrive in the middle of next week. I have decided to change all my internal signal wiring to a highly shielded cable that should reduce the hum a lot! I will post pictures as the work progresses.

Originally posted by Mikael Abdellah I have ordered Alpha and CTS potentiometers that should arrive in the middle of next week. I have decided to change all my internal signal wiring to a highly shielded cable that should reduce the hum a lot! I will post pictures as the work progresses.

Speaking of scratchy pots,
I generally buy Alpha's because I can get them fast and easy.

On more than 1 occasion, I have had freshly built guitar amps that appeared to have a scratchy pot on the Hi Bright channel.

If I turned/increased the pot REALLY slow it would not make any noise, If I turned it fast it sounded really dirty.

It turned out to not actually be the pot but actually the tube in the V1 position. I replaced the tube, Noise gone.

Be careful adding shielded leads, I would only add them 1 at a time and test between additions. I as well as others I know have experienced that in some cases they actually induce noise.

The preamp is almost finished. At least the first stage of it. I chose the CTS potentiometers and the beautiful corona cable took care of most of the humm. There is a small amount of hum even with the HV switched of so I guess it's either from the heater supply or stray leakage from one of the, so far, not twisted AC leads. I will try and make a complete schematics later. I will also post some new pictures shortly. The only big thing left now is the VU meter. I still haven't decided how to build it but it will NOT be with 3914/3915 IC's.